The disciples went up to Jesus and asked, ‘Why do you talk to them in parables?’ ‘Because’ he replied, ‘the mysteries of the kingdom of heaven are revealed to you, but they are not revealed to them. For anyone who has will be given more, and he will have more than enough; but from anyone who has not, even what he has will be taken away. The reason I talk to them in parables is that they look without seeing and listen without hearing or understanding. So in their case this prophecy of Isaiah is being fulfilled:

You will listen and listen again, but not understand,
see and see again, but not perceive.
For the heart of this nation has grown coarse,
their ears are dull of hearing, and they have shut their eyes,
for fear they should see with their eyes,
hear with their ears,
understand with their heart,
and be converted
and be healed by me.

‘But happy are your eyes because they see, your ears because they hear! I tell you solemnly, many prophets and holy men longed to see what you see, and never saw it; to hear what you hear, and never heard it.’